In known storage-type water heaters, potable water is commonly heated inside a holding tank with either a gas heater or an electric heating element. The temperature of the water is usually monitored with a thermostat that is operatively interconnected with the source of gas for the gas heater, or the source of electricity for the electric heating element. In order to conserve energy and fuel, the gas heater or electric heating element is actuated only when the temperature of the water falls below a selected minimum temperature.